A large outbreak of Shigella sonnei gastroenteritis associated with consumption of fresh pasteurised milk cheese.

A large outbreak of Shigella sonnei gastroenteritis occurred in Murcia Region (Southeast Spain) in the winter of 1995-1996. More than 200 people were affected. Epidemiological investigations implicated a regionally manufactured fresh pasteurised milk cheese as the vehicle of infection. A case-control study showed a statistically significant association between the illness and consumption of the suspect cheese. The dispersed sale of the cheese resulted in a regional dissemination of the organism and people were affected in eight townships. Research suggested that an infected foodhandler at the cheese factory might have been the source of contamination and that the processing method might have allowed cross-contamination to occur. This study emphasises the importance of increasing the control of strict hygiene during the processing of fresh cheese, since legislation does not forbid direct contact by hand that could result in contamination of cheese even when the milk pasteurisation process was correctly performed.